The embodiments described herein relate generally to electric vehicles and, more specifically, to methods and systems for charging an electric vehicle.
In response to increasing fuel costs related to the use of conventional combustion engine vehicles and in response to heightened environmental concerns, including air pollution, the use of electric vehicles has increased. As a result, energy demand will likely increase in the form of electrical energy used to charge batteries or other energy storage devices used in such vehicles. Typically, an electric vehicle owner has two options for vehicle charging. The electric vehicle may be coupled to a standard residential electrical outlet, which provides, in the example of the United States of America, 120 volts of alternating current (VAC) at approximately 15-20 amperes. A residence may also include a higher power connection to the power grid, for example, in the form of an electric vehicle charging station. The electric vehicle charging station may provide, for example, 240 VAC at approximately 30-32 amperes. The higher power provided by the vehicle charging station facilitates a quicker charging cycle for the electric vehicle than provided by the standard electrical outlet.
The higher power drawn by the electric vehicle through the charging station also increases the strain on power grid components, for example, distribution transformers. A distribution transformer reduces a primary voltage of the electric distribution system to the utilization voltage serving the consumer. Typically, a distribution transformer serves approximately seven to ten residences. The distribution transformer may experience greater loss-of-life (i.e., the useful life of the power grid component may be reduced) due to the increased demand caused by electric vehicle charging. The expected use of electric vehicles will add to the increased strain on power grid components. For example, individual employment schedules vary, however, as indicated by typical use of roadways and traffic flow, a majority of motorists return to a residence from a place of business in the early evening. It is expected that a majority of electric vehicle owners will desire to charge their electric vehicle upon returning to their residence from their place of business. An electric vehicle charged at 240 VAC and approximately 30-32 amperes is likely to create a larger individual residential electrical load than any other residential electrical load. Furthermore, if multiple residences served by a single distribution transformer include a vehicle charging station, the power demand created by charging of electric vehicles may cause the distribution transformer to overload, which in turn, reduces the lifecycle of the distribution transformer.